Oil can be refined generally by catalytic degradation or catalytic hydrogenation. Catalytic degradation is usually performed under atmospheric pressure at a high temperature. Liquid fuel can be obtained by controlling the vaporized hydrocarbons by catalytic pores. The yield is usually about 25 wt %. On the other hand, catalytic hydrogenation is usually performed under high pressure at a high temperature, for example, at a temperature of about 300° C. to about 500° C., and under a pressure of about 5 MPa to about 30 MPa (about 50 atm to about 200 atm.). Catalysts used in catalytic hydrogenation include noble metal, metal sulfide, and etc. However, these catalysts are usually difficult to be recycled. Moreover, conversion rate of oil is usually between about 30 wt % and 70 wt % depending on the catalyst used and reaction condition.
In general, chemical compositions of biomass oil and waste oil (including waste lubricating oil, waste turbine oil, or the like) are complex and are difficult to be used directly for their high oxygen content, low heat value (about 3000 kcal/kg to about 4000 kcal/kg), and high viscosity (over 40 cps.) Therefore, the oil needs to be refined before recycling.
However, although refined biomass oil and waste oil can be recycled as an alternative energy source, the oil refining process requires high temperature, high pressure, and expensive catalysts and has a poor oil conversion rate and thus can not meet commercial requirements.
Therefore, a novel method for refining oil with lower operation temperature and pressure is desired.